The present invention relates to semiconductor circuit fabrication technology, and more particularly, to protection and sealing of circuit elements using a cap and gasket.
Semiconductor circuits and devices are often manufactured on a substrate material by depositing and patterning various layers of material including conducting and semi-conducting material as well as insulating material. These circuits are typically very small (having dimensions in micron range or smaller), fragile, and susceptible to environmental factors (such as corrosion by interaction with water molecules in the air). Accordingly, in some applications, it would be preferable to protect the circuits by hermetically sealing the circuits using a sealing cap.
Such sealing can be accomplished using a gasket between the cap and the device chip. FIG. 1 illustrates an apparatus 100 including a device chip 110 including circuits covered by a cap 120 sealed using a gasket 130. The gasket 130 can be very thin, for example, in the order of tens of microns. To seal the device chip 110 using the cap 120 and the gasket 130, the cap 120 and the gasket 130 is pressed onto the device chip 110. The pressured is distributed to the entire surface of the contact area between the gasket 130 and the device chip 110. Accordingly, pressure per square unit of the contact area is relatively low. For this reason, placement of the cap 120 onto the device chip 110 can result in marginal or poor sealing of the gasket 130 to the device chip 110, resulting from inadequate pressure. Further, small foreign particles between the gasket 130 and the device chip 110 can breach the seal 132.
Accordingly, there remains a need for a method of fabricating semiconductor devices that overcomes these problems and an apparatus embodying the method.
The need is met by the present invention. According to a first aspect of the present invention, an apparatus has a device chip including circuit elements fabricated on a substrate and a cap covering at least a portion of the device chip. A gasket with treaded surface seals the cap to the device chip.
According to a second aspect of the present invention, an apparatus includes a device chip including circuit elements and a cap covering at least a portion of the device chip. The device chip has treaded surface for sealing the cap to the device chip.
According to a third aspect of the present invention, a method of fabricating an apparatus is disclosed. First, a device chip including circuit elements on a substrate is fabricated. Then, the circuit elements are enclosed using a cap and a gasket, the cap covering at least a portion of the device chip, and the gasket having treaded surface.
Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in combination with the accompanying drawings, illustrating by way of example the principles of the invention.